Carburetor structure



Aug-D 27, 1940' G, M.BICKNELL CARBURETOR STRUCTURE Filei March 20, 1937 2 Sheets-Sheet l 7, 1940. G. M. BICKNELL 2,213,036

CARBURETOR STRUCTURE Filed March 20, 1937 2 Sheets-Sheet 2 I/ VEN TOE azoeac M fizz/val.

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6 Troy v5 Y Patented Aug. 27, 1940 UNITED STATES PATENT 'oFFlc-E,"

CARBURETOR STRUCTURE Application March 20, 1937, Serial No. 132,048 3 Claims. (Cl. 261-70) This invention relates to carburetors for internal combustion engines and consists, particularly, in novel carburetor float bowl construction. I

,The modern automotive carburetor is usually provided with a mixture conduit supplied with liquid fuel from an adjacent atmospheric bowl or chamber connected to the fuel pump, or other remote source of fuel, through an inlet controlled by float actuated needle valve mechanism- .The main nozzle discharging into the mixture conduit communicates with the bowl through an orifice, usually metered or calibrated, located near the bottom of the bowl. With this arrangement the liquid fuel supplied to the mixture conduit varies, in general, with the suction in the conduit, the bowl pressure remaining substantially constant. If, for any reason, the level in the bowl is substantially varied, even momentarily, the mixture supplied to the engine by the carburetor is affected.

In some constructions, substantial space is provided above the fuel level and around the float and in these the liquid fuel level is subject to a variation due to operation of the carburetor at an angle and also due to surging, caused by a sudden change 01' momentum or direction. In some cases it has been found that surging and tilting, as described, have caused noticeable hesitation, missing, or even stalling of the engine due to excess leaning or enrichment of the mixture.

An object of the present invention is to provide carburetor float bowl construction which overcomes the above defects. A more detailed object is to provide a carburetor float bowl cover arranged to closely fit above and around the float so as to reduce the open space above the fuel level and reduce surging in the bowl to a minimum. These objects and other more detailed objects hereafter appearing are attained substantially by the structure illustrated in the accompanying drawings in which:

Figure 1 is a vertical section through a carburetor embodying the invention.

Figure 2 is a similar section taken on the line 22 of Figure 1.

Figure 3 is a top view, partly in plan and partly in section on the line 3-3 of Figure 1, and

Figure 4 is an underside view of the bowl cover, disassembled.

The carburetor shown includes a downdraft mixture conduit formed by air inlet horn l, venturis 2, mixing chamber 3 and outlet portion 4, flanged as at 5 for attachment to the intake manifold (not shown) of an associated gine.

Adjacent the mixing conduit is a bowl 8 within which fuel is maintained at a substantially constant level x-a: by needle'valve mechanism 1, controlled by a float '8, which is substantially smaller, than the interior of the bowl so as not 5 to unduly restrict the capacity thereof. The inner side of the bowl is recessed as at 9, and provided at the bottom of the recess substan-- tially beneath the fuel level with a calibrated orifice or let l0 communicating with an inclined l0 passa e II. A, screen 9;: extends across the open side of recess 9. 'I'hreadedly secured in passage i2 is the main fuel nozzle I 3. A stepped metering rod, shown in part at Illa, Fig. 2, extends into Jet 10 and may be controlled by suction or 5 from the throttle in any well known manner.

Also communicating withpassage I2 is a vertical passage M in boss Ila which, with trans.- verse passage l5, formsa part of the usual idling system terminating in oneor more ports (not shown) adjacent the throttle valve I 8. The two smaller venturis within the mixture conduit are supported by flns l1 and l8, thelatter extending beneath main nozzle It. A butterfly-choke valve I9 is mounted in the air horn and may be controlled by any suitable manual or automatic means (not shown).

Bowl '6 is provided with a separately formed top wall or cover, generally indicated at 20, having an apertured boss 2| at one side receiving the needle valve mechanism and the connection with a fuel supply conduit (not shown). A part 22 also projects above the bowl and has a central recess 23 terminating in-oriflce 24 substantially above the fuel level for exposing the 85 interior of the bowl to atmosphere. Recessed part 22 terminates inside cover 22a which protects carburetor mechanism (not shown) for operating metering rod Mia and the accelerating pump. The cover rests on and is secured to the bowl walls substantially above the fuel levelin the bowl so as to minimize the possibility of leakage past the bowl cover gasket.

The under surface of cover is provided with a depressed or hollowed portion 25 which extends rather closely above float 8 and through which atmospheric recess 23 communicates. Depending from the cover around portion 25 thereof are the projecting filler structures 28, 26a, 21 and 28 which preferably, though not necessarily, extend 60 slightly below the normal fuel level in the bowl and fit rather closely, around float 8. These filler projections thus substantially'flll the otherwise open spaces between the float and the bowl walls above the fuel level.

Filler structure 26, 28a is recessed, as at 29, to accommodate pivotal float supports Ill and tongue 3| controlling the needle valve. Accelerating pump cylinder 32 is substantially surrounded by fuel space for cooling the liquid within the cylinder so as to reduce percolation losses through the accelerating system. Filler structure 21 extends around and is recessed to accommodate the pump cylinder. The outer side of float 8 is located close to the outer wall of the bowl and no filler structure is provided in this space. Thus the especially formed cover structure, including the filler portions, extends closely around and above the float, only sufllcient open space being provided to prevent engagement and interference between the float and bowl or cover under normal operating conditions.

Screen 9a functions as a fuel cleaner and may be made of sufficiently fine mesh to lessen the undesirable effects of surging and tilting by momentarily trapping a quantity of liquid fuel in metering jet recess 8. The open fuel space beneath projecting structure 26, 26A substantially balances the fuel space at the opposite end of the bowl including the space around cylinder 32 and this, together with the minimum free air space above the fuel level, tends to minimize relative motion of the liquid fuel in the bowl due to inertia. Metering orifice III is preferably located centrally of the fuel space, relative to the longitudinal dimension of the bowl.

Obviously the cover construction and, particularly, the arrangement of the flller portions, may be varied in accordance with the particular carburetor design. In some cases, the extent of the filler means around the float may be'substantially increased or decreased depending upon the amount of space between the float and sides of the bowl above the fuel level, applicant's idea being to leave only a minimum of air space around the top of the float and beneath the bowl cover. The exclusive use of all such modifications as come within the scope of the appended claims is contemplated.

I claim:

1. In a carburetor, a float bowl, a float in said bowl and spaced substantially from the sides thereof, and a cover for said bowl extending closely above said float and resting on the wall of said bowl substantially above the normal fuel level therein, said cover having projections interposed between said float and the bowl walls and extending closely around said float, said portions terminating substantially above the bottom of said bowl but extending at least to the fuel level to provide fuel pockets beneath said portions, only suflicient free space being provided adjacent said float above the fuel level to permit normal float movements.

2. In a carburetor, a float bowl, 9. mixture conduit, a fuel supply passage opening into said bowl through the lower portion of a wall thereof, said wall having a recess above said opening, a float in said bowl. and a cover for said bowl resting on the bowl walls substantially above the normal fuel level in said bowl and closing said recess at the top, said cover having flller structure depending at least to the fuel level and between said float and the bowl walls and into the top portion of said recess so as to limit the free space in said bowl above the fuel level therein to only that which is sufficient to permit normal movements of said float.

3. In a carburetor, a float bowl. a float therein, an accelerating pump cylinder in said bowl and with a wall extending along the bowl wall, and a cover for said bowl resting on the bowl walls substantially above the normal fuel level in said bowl, said cover having flller structure depending below the normal fuel level and between the bowl and cylinder walls and said float so as to decrease the free space adjacent said float above the fuel level to the clearance necessary for normal float movements.

GEORGE M. BICKNELL. 

